Froma Harrop

The first part is undoubtedly true. Cats in the United States destroy a median of 2.4 billion birds a year. Add to that death toll 2.3 billion mammals, many of them native creatures: chipmunks, rabbits and voles, reptiles and amphibians.

These numbers came from a much-quoted report by scientists at the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service. They are several times higher than previous worrisome estimates.

Of more concern are colonies of cats living in the wild. Their human guardians may regard themselves as animal-rights activists, but the unflattering term for what they do is "subsidize predators." They are enabling an ecological crisis.

Most cats are not native to North America. They are a European and African import, introduced in the 19th century to control rodents. The International Union for Conservation of Nature lists cats among the world's 100 worst invasive species.

The researchers found that pet cats don't account for nearly as many kills as the feral ones. But all cats put together destroy more native wildlife than cars, pesticides, collisions with buildings and other human-related causes.

Some champions of feral cats do partly the right thing by having the animals neutered, then returned to the wild. But a cat's inability to reproduce does not curb its appetite.

Making the problem worse, cat owners no longer interested in caring for their pets often see cat colonies as a perfect dropping-off place. This, of course, adds to the roaming predator population. The American Bird Conservancy puts the number of homeless cats as high as 100 million.

Some solutions to the problem are not very amenable to cat lovers. (Cousin Janet in Dallas, forgive me for what I'm about to say.) In recent years, coyotes have greatly reduced my neighborhood's outdoor cat count. Sad what happened to Oscar and Buttons and the other feline faces peering down from "missing cat" posters. But the coyote visitation has led to an explosion of bird song.

Dingoes are another possibility. Studies from Australia, where these wild dogs flourished until farmers killed them, see dingoes as a possible savior of birds and other native animals. Researchers at Deakin University in Victoria found that dingoes eat cats and also scare them off, narrowing the window of cat-prowling time, especially right after dusk.

Suffice it to say, cats belong indoors. Whether cats are happier indoors is another matter, but there's no doubt that the beautiful community of winged creatures is safer when cats are watching from a window.

As for the human feeders of feral cats, please stop supporting the cat explosion.